One would guess lack of sun (prairie plants expect full sun) and possibly too much water ?

Can't be lack of sun (they are in full sun) As for too much water we are having the worst drought in 135 years. They are not new plantings they have done this for the past 2 years. It happens every year. I just spent a lot of $$ on supports. Any other causes (too little water??)

Not having seen your yard, this is just a guess. You might be growing isolated plants, and keeping the bed weeded. This would deprive the individual sunflower stalk of the support it would normally receive from being surround by other plants. Its all crowded together in a prairie, and they support each other. We have the same problem, I just tied up a sunflower to the porch the other day.

In my experience with my 2 1/2 year old native prairie planting I have noticed that several of the plants have gotten much larger than what I see in established prairies. I attribute this to lack of competition from other plants. Many of the plants I have including swamp milkweed, grey headed coneflower, sunflowers, stiff goldenrod, etc., have numerous flowering stalks whereas these same plants in their truly natural settings have but a single flowering stalk. The plants that are growing where I have heavy native grass coverage are not floppy and appear as I think they should. I'm hoping that as my plantings fill in the plants will flop less. In the meantime, I will be cutting the taller plants back so they are self supporting.

So should I plant grasses near the plants that are drooping?? Would this help support them?

Yes definatley..any prairie planting requires grasses :))

Vera

Here is a link that might be useful: Illinois Prairie Page

you have a very common situation. The prairie plants fall over in your yard due to a combination of reasons many of which have already been mentioned... not enough competition and fertile soil and age.

the prairie flowers need that competition or else they get lazy :-) There is no need for them to "strive to get vertical".

plantings near lawn areas that have been fertilized or in rich soils will produce large and numerous flowers that the young plant stalks cannot support.

you didnt say how old your plants were either. younger plants tend to fall over more than older plants... as the plants mature their stalks and bases tend to grow thicker and stouter. (but they still need those grasses)

I always have plants falling over, particularly the ones that are on the lawn edges or mowed border edges. They dont have the support and competition on the open side. I usually only pick them up or stake them if they are smothering something else that I am trying to get established.

Thanks for all the info one last question. My plants are about 2-3 years old. What grasses should I plant around the plants in particular compass plant, golden rod, laitris, downy sunflower, obedient plant? Should I plant the grasses on either side of the above listed? and how far apart? Any grasses that will grow under cup plants (Silphium perfoliatum) ???? Thanks for the help so far.

Big Bluestem, Little Bluestem, Side-Oats Grama, Indian Grass. They will help you out. April

In answer to the other part of your question, plant your grasses 12-18" apart, they will form clumps. You could plant any of these grasses under your s. perf.

April

i have a theory on this 'falling over'.

sure, the above ground support needs to somewhat be there. and grasses are a good solution to this. remember that a typical native ecosystem prairie had a general 70% grass to 30% forb ratio. but remember also that a prairie is like an iceburg, what is on top and u can see is only the 'tip of the iceburg'. u only see 10-20% of the biomass that is a 'prairie'. the real happenin's are in the soil. certainly there is no getting away from the fact that bigger roots = bigger and stronger shoots. and the only way to solve this problem is time. there is also the fact that a 15+ spp. per. sq. ft. is typical in a remnent and is pretty dense a stand vs a new prairie that has 2-5 spp per sq ft. tops. when i make a prairie, im happy with 2-4 spp. per sq ft the first 3-4 years. at 15, that's alot of roots binding onto one another, using eachother as anchors and maybe even working in tandom on some sort of symbiosis to solve a problem of nut's.
and in addition to that tangle of biomass under the soil, there is the line from soil to sun is somewhat fuzzy in a remnent. its not really soil but its not really all alive plants either. we call it thatch but its a conglomerate of root, stems, bugs and anything else that is 'prairie'. this is huge in an older planting vs a very young 'prairie' that even a 20 year old newly planted prairie is. this 'inbetween layer' becomes a type of scaffoling, supporting and even allowing smaller spp. (like birds foot violet) to be able to compete for the precious sun. you can see this in the many spp. that flop in my front yard where they get all the love they want but stand tall in older plantings where water and nut's are in short supply.

I agree with froggy about spp per sq ft and the roots need more time.

however on the thatch thing, I am confused. I dont think thatch is huge in an older prairie, unless it hasnt burned recently... thatch buildup is what fueled the fire.

If thatch is holding up the plants in a remnant, then wouldnt we see alot of plants falling over in the growing season after a burn?

that hasnt been my experience? perhaps you have noticed that?

Ok this may sound like a really dumb question but what is "15+ spp. per. sq." ? I understand the per square foot but what is "spp."?
please humor me on this ;->

spp. = species. sorry

and as to the 'thatch' on remnants, let me explain.

firstly, i am talking about tall grass, mid size grass eastern prairies. not the sand or the dry prairies of the west but the thicker ones of the east. i dont know if this is true out there but my guess it is just to a lesser extent.

on a newly planted prairie, when we burn it, there is a defined soil line, easy to see that its not root, rhizomes etc but soil like surrounding soil. clay, silt or sand and any combo of the 3.

but when u burn a long standing remnant, that soil line is much harder to discribe or define. a shovel full of it shows that the O layer is much different. firstly, there IS an O layer. this layer is comprised of what was once alive and is now; charred, 1/2 digested, not quite alive but maybe not fully dead, full o bacteria, worms and any other biota that i can think of. (forgive me but its been a LONG time from soils and i never really did well in it anyhow. so if im not using the jargen correctly...) u can feel this layer when even walking thru a remnant. even a newly burned one has a 'soft' feel to the soil surface.

vs what i like to call 'worked soil'. this worked soil includes just about anything we now live on. a plow mashes up all the layers into one and humans ped's them with salt and other human workings, like farming, lawns, road easements, old fields that were once farmed...again, just about anything that was touched by a plow relatively recently and not allowed to regain the O layer.

and its this O layer that im discribing as important to hold up smaller spp. (species) as a type of support. and also allowing big bluestem to grow to a height of 12 ft. vs maybe 6-7 ft on newly planted lands. yes, age is important, again as with iceburgs, the bigger the iceburg, the more stable the top will be. this is also true with plants. the O layer only comes with age.

froggy

I am getting a nice education on prairies here. Should I add grass and leave mulch to create the O layer faster, or just not clear the dead material out so thuroughly in the fall and spring?

u should add grass. almost cant have too much grass in a prairie.
and the only way to make that beautiful soil structure is to have it for about another 50+ years. letting ecology do what ecology does best.

froggy

I read somewhere that certain plants will flop if they planted near buildings even in full sun. I agree also with joepye that prairie plants that are pampered get lazy, plus they grow so dog gone fast and larger than usual (as ernestM said) I think they get stretched. I have pinched the heck out Goldenrod and Asters with some success, keeps them shorter and fuller. I have Indian, Big Blue Stem, and Sea Oat grasses that flop. IÂve tried cutting these back early in the season and it didnÂt help. IÂm going to do more experimenting next year.

My experience here in north-central OK is that native grasses don't flop if they're part of a thick stand, but do so when growing "alone." However my compass-plant and maximilian sunflower stems, which can grow to be 7' tall, invariably topple over once the flowers go to seed, even when they're surrounded by Indiangrass, big bluestem, etc. I've had the same problem with pale purple coneflower and Liatris. Very discouraging.

I agree on the Maximillian Sunflower toppling over...I don't have them planted in my wildflower area, but since it is a shortgrass area It wouldn't help with the toppling anyways! Any strong wind (and we get alot) and they blow over sprawling all over the place with or without being full of flowers!
I'm trying something new next year...I'm going to pinch them back a few times early one (like I did w/ my Hollyhock this year) to create shorter and bushier growth.

Vera